1. Field of the Invention
The invention is a process for the continuous esterification of C.sub.2 -C.sub.24 fatty acids with C.sub.1 -C.sub.5 monoalkanols or C.sub.2 -C.sub.3 dialkanols in the liquid phase, at an elevated temperature, in the presence of catalysts. The catalysts and the heated fatty acid are fed to the uppermost plate and the alkanols are introduced in the vapor phase above the sump at the lowermost plate of a multiple-plate reaction column followed by a rectifying section. The fatty acids and alkanols are reacted countercurrently over a residence time of the alkanols in the liquid phase of the reaction column of at least 20 minutes. A water/alkanol mixture is removed through the rectifying section and the fatty acid ester is removed from the sump of the column.
2. Statement of Related Art
Processes of the type mentioned above for the continuous esterification of fatty acids are known, cf. H. Stage, Chemiker-Ztg./Chem. Apparatur 87. No. 18, 661-666 (1963). This publication describes the esterification of fatty acids with methanol and n-butanol in multiplate reaction columns with steam baffle plates operated at normal pressure. However, the continuous esterification of fatty acids, on an industrial scale, is carried out in several stages in plate columns operated at pressures of from 5 to 30 bar, cf. DE-C 25 03 195.
It has been discovered that, in conventional processes for the continuous esterification of fatty acids, dehydration occurs to an unacceptable extent, for example where branched monoalkanols, such as isopropanol, are used. Accordingly, it is an object of the present invention to provide a process in which the unwanted secondary reactions are suppressed or substantially reduced.